So let's sum things up: The LOI and similar documentary terms, are non standard, confusing, and lead to ambiguity. Documentary ambiguity is referred to in trade law as a condition "The Battle of the Forms" in which confusion from contradictory and ambiguous forms and documents damages the transaction. This should be avoided. To seasoned corporate traders and bankers, using terms like "Letter of Intent" is the mark of amateurs. What you properly want is an RFQ, request for quotation, from a seller or supplier. The seller may then reply to your RFQ with a quote OR full offer if they wish.
Nowadays, to hear many of the oil sellers and operators, particularly their brokers and agents, who are involved in the international open market crude selling, describe it, this document _ called the "Letter of Intent" or LOI, for short _ is not only an essential document for doing crude oil business, but one which every credible person or company engaged in crude buying should always use in initiating a purchase. To many of these operators, not only should crude oil buyers use the LOI to initiate their buying orders, but initiating the purchase order in that manner, they say, has always been the usual way by which credible buyers initiate their purchasing projects, as doing it that way indicates, they claim, that a buyer is "serious" and genuinely committed to making a purchase.